


I'm not a science experiment

by Arerona



Series: Fellswitch [3]
Category: Undertale, Undertale (Video Game), fellswitch - Fandom
Genre: Science Experiments, evil scientist, fellswap, fellswitch, undertale - Freeform
Language: English
Status: In-Progress
Published: 2020-06-21
Updated: 2020-09-28
Packaged: 2021-03-03 20:14:34
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 3,568
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24831442
Author URL: https://archiveofourown.org/users/Arerona/pseuds/Arerona
Summary: A few years after absorbing a human soul Derringer is forced to undergo some experiments to try and heal the human soul that now resides in his own soul.
Series: Fellswitch [3]
Series URL: https://archiveofourown.org/series/1642120
Kudos: 1





	1. Chapter 1

Derringer stood in the dimly lit laboratory waiting for the scientist to enter, he didn't want to wait here but he didn't have a choice. After a few moments, a figure entered the room and began to prepare a few items on the desk ignoring the skeleton waiting for them.

"you going to speak to me or what?" Derringer huffed with his hands in his jacket pocket.

"Eager to get started huh?" The figure smiled coldly.

"no, i just want this over with..." he responded.

"As you wish..." The figure said then motioned to the metal table, "Take your jacket off." 

"humph..." he took his jacket off and set it on a chair.

"Shirt and boots too." 

Derringer glared at him before grudgingly slipping the shirt over his head and placing it on his jacket while kicking off his boots.

"Missing a few ribs there?" They pointed to the chipped ribs on his lower bones.

"ya can thank the queen for that..." Derringer rolled his eye lights as he sat on the table.

"Does it bother your breathing at all?" The scientist asked.

"...none of your business," He retorted.

"Suit yourself we just need to know if you'll need breathing help," the figure shrugged, "Lay down."

He huffed as he reluctantly laid flat against the table as the figure went to his feet and grabbed his leg this caused Derringer to shoot up and try to yank his leg away.

"hey! what gives?!" he exclaimed, "i didn't agree to..." 

"Lay back down," the scientist huffed as they pushed him back down, "This is for your own good we don't want you to injure yourself if you start thrashing..."

"thrashing?" Derringer said in surprise he figured this was going to be painful but the thought of being tied down made him nervous. 

"Yes, this procedure could possibly be painful..." they responded with mock sympathy.

"...figures..." he mumbled and put his legs where the cuffs were. 

The scientist locked his ankles in the cuffs before moving on to his arms and despite a weak attempt at protesting they locked his wrist in the cuff. Once they were done they disappeared and came back with a cart with a syringe and various other items on it.

"Now this will sting," they said before an assistant came into the room, "Yes?"

"Sorry to interrupt, Doctor, but we are having an issue with the other patient," the assistant said.

"Of course you would...I have to do everything ourselves..." They rubbed the sides of their nose and followed the other out of the room.

"hey! you could'a at least have givin' me a pillow!" Derringer called after them but his reply was the slam of the door, "humph..." he shifted on the table the small spines on his backbones caused him a lot of discomfort as he tried to adjust so they weren't directly on the table. He sighed and used magic to lift his shirt and jacket over to him and he nudged it under his head.  
"at least these don't restrict my magic..." he sighed as he waited.

He didn't know how much time had passed before he heard a loud scream that made him sit straight up or at least as much as he could. 

'i'm not the only one who he's experimenting on...' he thought as he focused on his wrists and popped one off his ulna and radial once his arm was freed he reattached his hand by gently touching his arm to his hand. Once reattached he started to fiddle with the other cuff when he got that freed he did the same with his legs. When he was able to he got up and headed for the door as soon as he got there he was greeted by the scientist who raised an eyebrow.

"what was that?" he asked.

"Nothing to concern yourself with, get back on the table," They said flatly pushing his shoulder.

"not until i find out who that was..." Derringer said as he started to push past them but the scientist put an arm out to bloke his way.

"Table. Now." they threatened. Derringer glared at them for a moment before sighing and returning to the table where the scientist cuffed him back down. They then turned their attention to the cart with the syringe and picked it up and filled it with a vile that Derringer didn't recall being on the cart before.

"and where are you going to inject that?" he asked shifting as a sense of dread started to fill his soul.

"Bring out your soul," they said flatly flicking the syringe.

"no... you're not injecting that mix there!" he retorted he didn't want a needle anywhere near his soul.

"Do it or else I will tell the Queen that you are not complying and maybe she'll have me find out why your little brother's eyelights flicker the way they do..." they smirked, "What's his name? Sans was it? Or do you prefer Nuke?"

Derringer glared at him if looks could dust a monster they'd be dead. Derringer had been blackmailed into this but his compliance didn't extend to his natural defense of his soul. He let out a huff and closed his eyes and tried to focus on his soul he didn't know if he could with how high his anxiety was but he knew the scientist would tell the queen. .

"I'm waiting..." they said tapping their foot.

"i..i'm trying... this... this isn't easy..." He didn't want to risk his brother's life so he had to try and he tried very hard

"Fine, we'll start with these," they attached a few wires that were on the cart to his ribcage and sternum.

"wha?!" Derringer startled and looked at his ribcage as they flipped a switch it sent a few low-level shocks around his body, "s...stop...p..please, w...why a...are y...you d..doing this t...to m..me!?" he hadn't expected this as he thrashed involuntarily against the restraints.

"I knew you'd need those," they smiled seemingly pleased by Derringer's reaction, "This is only a taste of what your little brother will feel if you don't comply."

"i...i s..said... i..i..i w..was t..rying..." he replied through shocks unable to gather his thoughts enough to summon his soul at this rate.

"We're waiting..." 

"s...s..top s...shocking me..." he muttered as the shocks slowly stopped he gasped trying to catch his 'breath' as he focused on summoning his soul. It took him a moment but soon his soul faintly appeared it was a grey upsidedown heart with a cracked blue soul inside.

"Ah finally... Hm, we see the human soul is extremely cracked... This serum might need to be increased," They said as they lightly took his soul in their gloved hands.

"d..don't..t..touch..." Derringer mumbled as he felt a rush of emotions that weren't his. Even though the scientist was wearing gloves with his soul bare he could faintly feel the other's cold emotions. The scientist was a Siphonophorae type monster they were a colony of thousands of microscopic monsters that formed a whole creature. Derringer had thought that one of them might have felt some remorse but all he felt was ice and... something else arrogance? Hate? He couldn't tell, there wasn't a strong connection which he was grateful for. 

"Oh don't over-exaggerated the sensitivity of the soul," they said condescendingly as they prepared the syringe.  
"This might sting," they warned.

"sting?! you're going to stab my soul with that needle and you say it might sting?!" Derringer protested trying to not let his nerves get the best of, "you're a master of understateme.. urk!?" 

As he spoke the scientist injected the needle into his soul and began to move the needle around the blue soul. Causing the green serum to circle the blue soul besides the pain it made him feel ill. Derringer began to thrash he tried to resist but it was involuntary because he was in so much pain. 

"On a scale of one to ten, how much pain are you in?"

"t..ten!" Derringer shouted trying to keep his composure, “p..please ta..ke i..t o..out!” 

“I see…,” they said making a little note on a sheet of paper. “We’re sorry but we have to move it around to ensure the best spread of the serum.”

He didn’t respond as he tried to focus on braving the pain as it seemed to encompass his whole body. The scientist didn’t have any mercy as he moved the needle around the small blue soul feeling the grey soul with a sickly green. Derringer closed his eyes tightly he didn’t want to watch as the green spread, he wasn’t sure if whatever they injected would have lasting effects. He didn't realize it until he heard the scientist gasped as Catster appeared and sent a blast of magic at them.

"We didn't think you would actually try to attack us," they huffed as a force shield surrounded Catster as she lunged at him.

"d.. didn't m..mean t...to...s..she senses m...my pain..." He replied looking at his blaster try to claw her way out.

"Interesting..." They removed the needle and went over to a console and studied the Blaster for a moment. They twisted a few knobs and the force shield around Catster sparked to life, she hissed and growled as she tried to out.

"S..stop!" Derringer yelled as he struggled to get up.  
"y... you're h...hurting her!" 

"What would happen if I dust it?" They asked twisting the knob to intensify the shocks, "I know other skeleton's are still able to summon blaster after being destroyed but we've never seen any like her before. So you might not be able to resummon it."

"d.. don't know! s..she wasn't part of the d..deal! Let Her GO!" 

"Let's see what would happen shall we?" They smiled cruelly as they turned the know to full power. Derringer eyelights flickered as he watched his beloved blaster writhe in pain, he could feel it as he tried to focus enough to send her back home.

"n...no! p..please! i... i don't know what will happen!" He almost begged, "i...i could lose her!" He didn't know if the serum would inhibit his ability to summon her from his magic again. 

"It's for science this way you'll know if you can summon her again if she is destroyed..." they said flatly as Catster fell on her side breathing heavily the shocks wearing her down. 

Derringer growled as he used his remaining power to try and send her safely home. She disappeared and he could sense she was back safe at home and with that he slipped into unconsciousness.

He awoke to a sharp pain on his rib cage as the scientist poked a needle into his sternum.

"wha?! huh?!" He startled before realizing where he was and what was happening.

"Interesting... You spent the last bit of your energy to save your blaster... Hm, and you managed to break our magic inhibitor shield... Seems to us that there's more to you than meets the eye."

Derringer didn't dignify that with an answer he settled for staring at the ceiling. Wondering how much longer he would have to suffer this indignity. 

"Are you angry with us?" The scientist asked.

"... y..you g..got to be kidding me?!" Derringer growled having regained a bit of strength from his 'nap'. "you and the queen threaten my brother and i just so you can do your cruel experiments on my soul with the human soul... try to dust my blaster and you have the nerve to ask if i'm angry with you all?!"

"We'll take that as a yes then," they shrugged and turned away. He hadn't realized that they still had his soul but soon felt it as they gave it a painful squeeze.

"n..hn urk..." It felt like someone was trying to crush him he couldn't help but scream as the pressure increased.

"Don't raise your voice to us again." They said flatly as they released his soul it swiftly disappeared into Derringer's ribcage, "We're done for today, you may leave." 

They removed the electrodes on his ribcage before they released his cuffs on both his arms and legs. He didn't move right away, regaining his composure as he sat up and inches off the table. He tried to stand but stumbled because his legs were numb and from the use of so much energy. 

"Undyne come here," the scientist said through an intercom a short time later Undyne entered.

"Y...yes S ..ir?" She asked.

"See to it he gets home... I don't want something to dust him before we can see if our serum works," they said as they turned to Derringer, "We expect you back in one week to see the progress..."

"if i live that long..." He replied as Undyne helped him out the door.

"A..are you a.. alright?" She asked quietly.

"...other than feeling violated and exhausted i'm just peachy..." He said harshly. He didn't really mean to come off as harsh but he was in pain and wasn't himself.

"I.. I'm sorry..." She said sadly.

"not your fault it's theirs..." He stated flatly as they reached the lab's front door.

"S..still... Y...you deserve b...better..." She sighed.

"i don't believe i do anymore... seems i'm doomed to suffer... i must have done something terrible as a child to deserve this..." He muttered.

"D... don't say that!" She scolded, "Y...you were a perfect child..."

"thanks for your praise but i was far from perfect... " He sighed as he pulled away from her, "thanks for the hand but i can make it from here if anyone sees you helping me it could be trouble for the both of us."

"A..are you s..sure?" She asked.

"yeah, i've been beaten worse and made it home," He said with a slight smile as he disappeared leaving her alone in front of the laboratory, she sighed as she reentered the labs.

His trip to his home was surprisingly uneventful considering the day's events on his bed, Catster was curled up sleeping.

"h...hey girl, how are you feeling?" he said giving her a gentle rub on the head. She looked up at him and head-butted him gently, "i...i don't know what would've happened, but i'm glad you got out of there..."

He flopped onto the bed beside her as he sighed, he was exhausted and just wanted to sleep. But he had to know if Nuke was alright so he grabbed his phone and called Muffet who was babysitting.

"He's fine," she said without giving him a chance to ask. It was something she was used to so she found it best to get to the point, "Are you coming over to pick him up?"

"Muffet... can, can you keep him tonight?" he asked quietly.

"Of course," she replied it wasn't the first time he'd ask that and knew better than to ask him anymore.

"...thanks, tell him good night for me," he said before hanging up and drifting off into a restless sleep.


	2. Under the Microscope

“You’re late...” the scientist huffed.

“didn’t want to come,” Derringer said with an equally annoyed huff, 

“You know the drill by now, don’t waste our time,”

“Yeah yeah...” he replied as he removed his jacket and shirt as well as his boots. Once they were off he went over to the metal table and laid down, the flat table hurt his vertebrae.

“Finally realized it would go much quicker if you cooperated huh?” they said as they latched the cuffs around his arms and legs.

“just hurry up i have things to do…” Derringer sighed.

“Your only thing to do is to lay here and be silent!” they retorted as they put electrodes on his ribcage.

“huffy today huh?” this earned him a strong shock that sent his body convulsing.

“Be silent!” the scientist growled. 

He held in the urge to scream even though it hurt like crazy he wouldn’t give them the satisfaction.

“Today we have a guest...” They said after the shocks stopped.

“w...who?” His morrow froze when he saw the queen enter, his gaze shot up to the ceiling trying to focus enough not to show how terrified he was at seeing the queen while he was bound to the table. 

“Is that any way to greet your Queen?” she said as she approached him and towered over him.

“forgive me for not bowing… i’m a bit tied up at the moment...” he replied staring at the ceiling.

“Look AT ME!” She huffed as she grabbed his chin and yanked him to face her.

“yes, ma’m,” he growled as she dug her nails into his jaw bone.

“How has the serum been working?” she asked.

“Well,” they replied, “Summon your soul for us so we can see your progress...”

A tinge of fear rippled through him, he didn’t want the queen anywhere near his soul.  
“i’d rather not... there hasn’t been any change… i assure you,” Derringer protested.

“Oh get over it,” she huffed, “Summon your soul!”

He went rigid as he focused on the ceiling he didn’t want to summon his soul but he knew at this point it was going to be worse for him if he didn’t. So he focused, as he did the soul flickered and appeared above him, but when the scientist reached to grab it his soul disappeared.

“...Really now? We’ve been through this before...” They said impassively as they pressed a button and Derringer started to thrash. 

“hng!” he tried to resist screaming but he hated being shocked and he couldn’t compose himself to not scream.

“Hurry up Don’t waste my time!” The queen growled.

He nodded once the shocks stopped and he tried again this time his soul appeared, the scientist quickly grabbed it with a gloved hand. 

“Hm… it looks like there is some change,” They said as they examined it, but Derringer could tell they were lying. Not only could he feel the deceit through the glove but he’d come to learn body language.

“How much?!” The queen huffed.

“Marginally, but after a few more doses… But we’ll increase the dosage in order to decrease the time it takes.”

“Let me see his soul,” she replied with a huff the scientist handed over the soul to her, Derringer tried to pull his soul away from her but she held it tight with the thick gloves she had put on. Even though she was wearing the gloves he could still feel her malice and hate, it made him nauseous. His soul flickered and jittered as he couldn’t hide his fear in his soul or fake its a calm demeanor.  
“Are you scared?” the queen mocked Derringer didn’t respond instead he just stared at the ceiling trying to block out what he could. But he was yanked back to the present when he felt like he was being crushed.  
“Answer ME,” she growled crushing his soul.

“y..you are squeezing m...my soul! h..how can i...i!” 

She gave a huff like what he was asking was a mild inconvenience. She relaxed her squeeze enough that now his soul was just floating in her hand.  
“Go on as you were,” she said with a huff to the scientist. They nodded and took the syringe from the table and filled it with something from a green vial. Derringer couldn’t help but close his eyes as they injected his soul with the green substance. He felt sick as it swirled and began to fuse with the blueness of the human soul within his. He wanted to be anywhere else then her under the threatening gaze of the queen and scientist. He didn’t hear what the pair discussed afterward but he couldn’t move as the two left the room. He didn’t know how long they were gone but soon the scientist came back in and took another needle and plunged it into Derringer’s soul without a word. He screamed at the suddenness of it unable to compose himself as the scientist pulled back on the needle plunger removing some of his magic as well as the blue soul. 

“Interesting...” the scientist said as they walked over to a table with a microscope and began to examine it. They jotted down plenty of notes passively as Derringer desperately tried to hold himself together. He wanted to leave but he was still strapped to the table and he didn’t have the strength to just shortcut away. He didn’t know how long he laid there but finally, the scientist came back and unlatched the cuffs and simply walked away. Derringer rolled to his side and forced himself up, he still couldn’t ‘breath’ as he got to his feet. He was lightheaded as he slowly walked out of the room, he just wanted to get home to Nuke now. As soon as he stepped out his phone rang… It was the queen, he let out a sigh as he answered it.

“My throne room NOW!” she growled and hung up before he could say a word. He shook his head, seems he’d be in for some more trouble as he headed to the castle....

**Author's Note:**

> Derringer is around 22 -23 years old.  
> He's been the Queen's enforcer for 2-3 years.


End file.
